Microstructure and electro-optical properties of sol–gel derived Cd-doped ZnO films

The microstructure, and the electrical and optical properties of undoped zinc oxide (ZnO) and cadmium-doped ZnO (CZO) films deposited by a sol–gel method have been investigated. The films have a polycrystalline structure with hexagonal wurtzite ZnO. Scanning electron microscopy (SEM) images indicated that the films have a wrinkle network with uniform size distributions. The elemental analyses of the CZO films were carried out by energy dispersive X-ray analysis. The fundamental absorption edge changed with doping. The optical band gap of the films decreased with Cd dopant. The optical constants of the films such as refractive index, extinction coefficient and dielectric constants changed with Cd dopant. A two-probe method was used to investigate the electrical properties, and the effect of Cd content on the electrical properties was investigated. The electrical conductivity of the films was improved by incorporation of Cd in the ZnO film.     

Effective and Functional Surface Design for Biosensing Applications Based on a Novel Conducting Polymer and PMMA/Clay Nanocomposite

Surface functionalization plays a crucial role in the design of biosensors. For this purpose, a novel functional monomer, 6‐(4,7‐bis(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐5‐yl)‐2H‐benzo[d][1,2,3]triazol‐2‐yl)hexan‐1‐amine (BEDOA‐6), was designed and synthesized. Poly(BEDOA‐6) was utilized as an immobilization matrix for glucose oxidase biosensor construction. Moreover, polymethylmethacrylate (PMMA) layered silicate nanocomposites were prepared by in situ suspension polymerization. Conducting polymer surface was modified with PMMA/clay nanocomposite material and a glucose biosensor was developed. In addition, XPS and SEM were utilized to characterize the surface properties. The biosensor shows a wide linear range between 2.8 µM and 1.2 mM to glucose with a low detection limit of 1.99 µM. Finally, the biosensor was tested on serum samples containing actual human blood. The results were in well‐agreement with a reference method.     

The Synthesis of Sulfinylphthalimides and their Reactions with Some Nucleophiles in Dioxane

Abstract

In this study, some N-(p-substituted-arylsulfinyl)phthalimides (1a–1e) were synthesized. The synthesized compounds were examined with respect to their substitution reactions with sodium ethoxide, sodium methoxide, methylamine, and t-butylamine in dioxane. The substituent effect was investigated at 30.0 ± 0.1 °C. The activation entropy was also studied, and negative ΔS^≠ values were obtained. Configuration inversions were observed in the substitution reactions. This result is in conformity with the S_N2 mechanism.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Characterization of -(p-Substituted-arylsulfinyl)phthalimides 1a–b.]     

Bis benzothiophene Schiff bases: synthesis and in silico-guided biological activity studies

Since benzo [ b ] thiophene scaffold is one of the privileged structures in drug discovery as this core exhibitsactivities for different biological problems, in this study bis (benzo[ b ]thiophene-2-yl) alkyl methanimine derivatives (1-9) were synthesized by reacting benzo[ b ]thiophene-2-carbaldehyde with diamines. All newly compounds were characterized by IR, ¹H NMR and ¹³C NMR spectroscopic methods. Synthesized compounds were investigated using binary QSARbased models on therapeutic activity prediction of synthesized compounds and they showed high predicted activities in following diseases: bacterial, angina, allergy, depression and obesity. Thus, they were then tested for their antimicrobial and antileishmanial activities as a result of this theoretical study. Compound 1(N, N’- (propane-1,3-diyl) bis (1-(benzo [ b ] thiophene-2-yl)) methanimine) was found the most active compound in both diseases. Thus, its molecular docking studies were also carried out.     

A new donor‐acceptor type polymeric material from a thiophene derivative and its electrochromic properties

A new electrochromic polymer, poly(2,3,5,8‐tetra(thiophen‐2‐yl)quinoxaline) (PTTQ), was synthesized electrochemically and its electrochromic properties were investigated. The polymer was characterized by Cyclic Voltammetry, Fourier Transform infrared spectroscopy, UV‐Vis‐NIR Spectroscopy, and colorimetry. Spectroelectrochemistry analysis demonstrated that the polymer can undergo both p‐ and true n‐type doping processes. The polymer, (PTTQ), has three accessible color states: an oxidized transmissive, a neutral light bluish‐green, and a reduced transmissive light gray. Switching ability of the polymer was evaluated by kinetic studies. The polymer revealed an excellent optical contrast of 98% in the NIR region. Outstanding optical contrast in the NIR region, high stability and fast switching times make this polymer an excellent candidate for NIR device applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3723–3731, 2008     

Investigating the competitive assumption of Multinomial Logit models of brand choice by nonparametric modeling

Summary  The Multinomial Logit (MNL) model is still the only viable option to study nonlinear responsiveness of utility to covariates nonparametrically. This research investigates whether MNL structure of inter-brand competition is a reasonable assumption, so that when the utility function is estimated nonparametrically, the IIA assumption does not bias the result. For this purpose, the authors compare the performance of two comparable nonparametric choice models that differ in one aspect: one assumes MNL competitive structure and the other infers the pattern of brands? competition nonparametrically from data.     

Phosphorus-nitrogen compounds part 22. Syntheses, structural investigations, biological activities and DNA interactions of new mono and bis (4-fluorobenzyl) spirocyclophosphazenes

The reactions of hexachlorocyclotriphosphazene, N₃P₃Cl₆, with mono (1 and 2) and bis(4-fluorobenzyl) diamines (3-5), FPhCH₂NH(CH₂)_nNHR (RH or FPhCH₂-), produce mono (1a and 2a) and bis(4-fluorobenzyl) monospirocyclophosphazenes (3a-5a). The tetraaminomonospirocyclophosphazenes (1b-2d) are obtained from the reactions of the partly substituted phosphazenes (1a and 2a) with excess pyrrolidine, morpholine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD), respectively. The tetrachlorobis(4-fluorobenzyl) monospirocyclophosphazenes (4a and 5a) with excess pyrrolidine, morpholine and DASD afford the fully substituted bis(4-fluorobenzyl) monospirocyclophosphazenes (4b, 4d-5d) in boiling THF. In addition, monochlorobis(4-fluorobenzyl) monospirocyclophosphazenes (4e and 4f) have also been isolated from the reactions with excess morpholine and DASD in boiling THF. The structural investigations of the compounds have been verified by elemental analyses, MS, FTIR, ¹H, ¹³C, ¹⁹F (for 1d and 2d), ³¹P NMR, HSQC and HMBC techniques. The crystal structures of 3a, 4a, 5a and 2b have been determined by X-ray crystallography. The compounds 2a-5a, 1b-2d, 4b, 4d-5d, 4e and 4f have been screened for antibacterial effects on bacteria and for antifungal activity against yeast strains. The compounds 1b and 4b showed antimicrobial activity against three species of bacteria, Bacillus subtilis, Bacillus cereus and Staphylococcus aureus, and two fungi, Candida albicans and Candida tropicalis. Minimum inhibitory concentrations (MIC) were determined for 1b and 4b. The MIC values were found to be 5000 μM for each bacteria. The most effective compound, 4b has exhibited activity with a MIC of 312 μM for C. albicans and 625 μM for C. tropicalis. DNA-binding and the nature of the interaction with pBR322 plasmid DNA are studied. All of the compounds induce changes on the DNA mobility and intensity. Prevention of HindIII digestion with the compounds indicates that the compounds bind with AT nucleotides in DNA.     

Azathia crown ethers carrying pyrene pendant as receptor molecules for metal sensor systems

A series of crown ethers carrying a pyrene group with nitrogen–sulfur donor atoms, that differ in having three, four and five sulfur atoms in the macrocycle was designed and synthesized by the reaction of the corresponding macrocyclic compound and 1-bromomethylpyrene. The influence of metal cations such as Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺ and Al³⁺ on the spectroscopic properties of the ligands was investigated in acetonitrile–dichloromethane (1:1) by means of absorption and emission spectrometry. Absorption spectra show isosbestic points in the spectrophotometric titration of Fe²⁺, Zn²⁺, Cu²⁺, Pb²⁺ and Hg²⁺. The results of spectrophotometric titration experiments disclosed the complexation compositions and complex stability constants of the novel ligands with Fe²⁺, Zn²⁺, Cu²⁺, Pb²⁺ and Hg²⁺ cations. The monoazatetrathia crown ether showed good sensitivity for Cu²⁺ with linearity in the range 5.0×10^?7–2.5×10^?6 M and detection limit of 1.6×10^?8 M.     

Electron immigration from shallow traps to deep traps by tunnel mechanism on Seydi?ehir aluminas

In this study, the fading mechanism of Seydi?ehir alumina in Turkey, which is considered to be used for radiation dosimetric purposes, was investigated. The materials were first exposed to beta radiation and then stored in dark and dry ambient conditions at room temperature (RT) at previously desired storage periods. It was observed that the glow curve of Seydi?ehir alumina consists of four glow peaks between RT and 400 °C. The glow peaks (peaks 1, 2 and 3) between room temperature and 250 °C possessed very high levels of anomalous fading. However, the intensity of new glow peak at around 378 °C is highly increased with time. As a result of the experimental studies, it was concluded that the reason behind anomalous fading can be explained by means of tunneling (quantum tunneling) mechanism.